This invention relates to a new propeller assembly. The assembly is especially suited for lightweight, low airspeed aircraft such as that disclosed in my prior U.S. Pat. No. 3,930,624, but the assembly may be utilized in any propeller system in which the unique features of this invention provide an advantage.
In U.S. Pat. No. 3,930,624, issued Jan. 6, 1976, there is described a lightweight aircraft having a major longitudinal strength structure generally centralized in the vertical mid-plane. Shallow V-shaped wing panels are secured to this longitudinal strength structure, one at the top and one at the bottom, to define a rhombic, cellular wing configuration, viewed axially of the craft. Paired, positive-lift rhombic wings are disposed toward the ends of the aircraft and cooperate with a substantially triangulated aircraft frame.
The aircraft described in the aforesaid patent is exceptionally compact, possesses light weight with strength, light wing-loading, low landing speed, stability, safety, simplicity, ease of inspection, field adjustment and repair, and facility of control operation of the aircraft, all at moderate cost.
The thrust producing system of the aircraft depicted in U.S. Pat. No. 3,930,624 comprises a propeller mounted on a drive shaft extending between bearings located in the upwardly diverging central vertical braces of the aircraft wing assembly. The center of thrust of the propeller is substantially on the longitudinal axis of the fore and aft wings, near the center of drag of the aircraft. The propeller is driven by an engine (preferably two) connected by a chain or belt to the propeller drive shaft.
U.S. Pat. No. 1,154,649, issued Sept. 28, 1915, depicts a propeller in which the blades are adjustable to any desired pitch, which includes a propeller hub assembly in which the propeller blades are rotatably mounted and including means to hold the blades in their adjusted positions. This patent further provides a propeller in which the separate blades may be adjusted in exact relation with each other so that both of the blades will have the same pitch. The simplified design requires only drilling and cutting for manufacture.
U.S. Pat. No. 1,949,611, issued Mar. 6, 1934, depicts a propeller assembly in which the major portion of each blade is offset from the center line of the root of the blade whereby, during changing of the pitch angle of the blade, an actual raising and lowering movement of the blade tip is effected so that the desired pitch angle will be obtained throughout the length of the blade and permitting the blade to follow a geometrical helix during rotation.
U.S. Pat. No. 1,648,837, issued Nov. 8, 1927, provides a wind driven power plant in which propeller blades are driven under the control of governors which automatically regulate the pitch of the blades or vanes to provide even speed of the drive shaft operated by the blades regardless of wind speed. The propeller assembly, depicted in this patent is one in which the individual propeller blades are mounted in a hub and are offset from a common centerline, similar to the blade assembly depicted in the aforesaid U.S. Pat. No. 1,154,649.
None of these prior patents describe a propeller assembly in which the propeller blades are adjustable longitudinally along their axes, i.e. the span of the blades is adjustable, by adjusting the propeller shafts in the hub of the assembly to a desired position and locking the shafts thereat by means of set collars. In addition, none of these prior patents disclose a hub for a propeller assembly which is split transversely providing for disassembly and removal of the entire propeller assembly from the drive shaft without removing inboard or outboard shaft bearings or any other components. Such a propeller assembly is the subject of this invention.